Blister packages are well-known for storing and displaying articles. Blister packages are commonly comprised of a thin front sheet of plastic joined to a back sheet, such as foil, paper, plastic or cardboard. At least one raised receptacle or blister is formed in the thin plastic sheet which is sized and configured to hold on article. A portion of the back over the blister may be perforated to enable the article to be removed by opening that portion at the back. Other blister packages are opened by peeling the blister from the back. The blister package commonly has a hole through it to allow it to be hung on a rod. Typically, a number of such packages are held on a single rod.
Another type of blister package, called a clam shell pack, has a plastic front and back that are hinged together along one edge, typically the bottom edge. The front usually has one blister for holding the product. The unattached edges of the front and back are configured to lock together. An example of this type of blister package is disclosed in U.S. Pat. Nos. 4,739,883 and 5,573,117.
Blister packages are commonly used to package medicine. Typically, the front has multiple blisters each holding a single pill or lozenge. Examples of blister packages for dispensing medication can be found in U.S. Pat. Nos. 4,574,954; 4,492,792; 3,211,503 and 3,283,885. In recent years medicine has been packaged in blister packages sized to hold a single dose of medicine. These unit dose packages are popular in hospitals and nursing homes.
Most consumer packages today carry bar codes that can be automatically scanned to identify the item being purchased or used. The bar code of a unit dose medicine package may contain not only the product identification, but also the expiration date. Hospitals are increasingly using bar codes on unit dose packages to identify and record medicine given to each patient. U.S. Pat. No. 5,593,267 discloses an automated pharmacy in which unit dose medicine packages are stored on racks and retrieved by a robot. An automated picker locates and selects the packages containing prescribed medicine from storage rods at discreet locations in the storage area of the automated pharmacy. Most unit dose medicine packages are blister packages that have a bar code on the back which faces forward when the package is held on the storage rod. The robot has a bar code reader to identify each blister package as it is removed from a rod. To keep the blister packages spaced apart on the rod, blister packages used in the automated pharmacy have raised formations on the thin plastic sheet. One such package disclosed in our U.S. Pat. No. Des. 384,578 has such a projection on each upper corner with the medicine containing a blister centered in the bottom half of the package. This configuration equally spaces the blister packages on a storage rod. However, this raised formation also can cause certain problems when a number of such blister packages are loaded and held on such a storage rod. If the package is turned a sufficient amount to either side while hanging on the rod, the raised formation has a tendency to get caught on the top edge of an adjacent package. Then, the blister package hangs from the storage rod at an angle. When the robot attempts to retrieve the package the bar code on the blister package is not in the expected, relatively level position for it to be easily read by the bar code reader on the automated picker. The bar code reader may then read the bar code on the package behind the front package, conclude that no package is on the rod, or report that it is unable to find a package on the storage rod. Then, the operator may be required to stop the robot, enter the storage area and straighten the blister packages.
Thus, there is a need for a blister package which will not get caught on the top edge of an adjacent blister package and will hang vertically when stored on a rod.